1. Field of the Invention
This invention relates to a means for identifying blood types and preventing transfusion to a patient of a blood type incompatible with the blood of the patient. The device and method minimize the possibility of error in the retrieval, storage and subsequent transfusion of blood.
2. Description of the Prior Art.
(a) Patents.
Transfusion to a patient of blood which is incompatible with the blood type of that patient can cause a serious reaction and is sometimes fatal. The prior art teachings aimed at preventing that problem include U.S. Pat. Nos. 4,265,101 and 4,302,956 which describe devices designed to guard against the most frequent cause of incompatible blood transfusions--clerical errors.
U.S. Pat. No. 4,265,101 teaches a "holder bag" adapted to hold a bag of blood. The holder bag is completely sealed except for a locking cap. The locking cap operates much like a combination lock. The proper combination to release the cap, according to the teachings of this patent, is established by a blood bank technician at the time a pre-selected bag of blood is placed in the holder bag and dispatched from the blood bank to the patient's location. The blood bank technician sets the combination of the locking cap to correspond to the patient's identification number assigned at the time of admission to the hospital. Upon the arrival of the blood bag to the patient's location, the staff member who administers the transfusion must obtain the patient's identification number from the patient's wrist band and enter that number into the locking cap. The cap is thereby released and the staff member obtains access to the pre-selected blood bag.
U.S Pat. No. 4,302,956 teaches an improvement upon the holder bag patent. This patent teaches a different locking mechanism suitable for use with blood bags of the type having a lockable flap. The teachings of U.S. Pat. No. 4,302,956 are nearly the same as those of U.S. Pat. No. 4,265,101 except that a different mechanism is used for locking the pre-selected blood bag just prior to dispatch from the blood bank. Like the U.S. Pat. Nos. 4,265,101, 4,302,956 teaches a locking mechanism which operates by a combination lock. The patent teaches that the combination of each individual lock is to be set by blood bank technicians to correspond to the patient's identification number at the time a blood bag is dispatched from the blood bank. Upon arrival at the patient's location within the hospital, the locking device is released by entering the patient's identification number found on the wrist band of the patient.
The devices disclosed in U.S. Pat. Nos. 4,265,101 and 4,302,956 guard against clerical error in only one portion of the blood administration cycle. The devices merely help to prevent blood which is properly selected and dispatched from the blood bank from being delivered and administered to the wrong patient. However, these devices do nothing to prevent errors in other portions of the blood transfusion cycle.
Consider a typical transfusion cycle. Before a blood transfusion can be prepared and dispatched from the blood bank, the blood type of the patient who will receive the transfusion must be determined. As taught by these patents and typically done in practice, a blood sample is taken from the patient, labelled in some manner such as by name or identification number to identify its source and transported to a blood analysis laboratory. There, a lab technician analyzes the blood sample. The laboratory technician then relays to the blood bank the blood type and other information corresponding to the patient's name or other identifying characteristic such as the patient's identification number. The blood bank technician then selects a bag containing the appropriate blood type. At this point in the process, one of the locking devices of the above-described patents is used. The blood bank technician sets the combination to correspond to the identification number of the patient and dispatches the locked blood bag to the patient's location. Upon its arrival, the nurse unlocks the blood bag and administers the transfusion. It is obvious that only a portion of the cycle is benefitted by the devices disclosed in the above mentioned patents. They do nothing to prevent clerical errors between the time that the blood sample is drawn from the patient and the time that a blood bag is selected to be sent to the patient. It is an object of the present invention, therefore, to provide more complete protection and guard against clerical errors throughout the entire process.
(b) Non-Patent Prior Art.
Another item of prior art widely in use is a system distributed by Hollister Incorporated known as the "Ident-A-Blood Recipient System". The Ident-A-Blood System consists of labels and forms which are used according to a prescribed procedure. If the labels and forms are used in accordance with the procedure, the Ident-A-Blood System helps minimize the likelihood of clerical errors. The system does not contain any distinctive mechanisms or devices; it consists only of labels and forms.
The Ident-A-Blood System is not easy to explain. However, the Ident-A-Blood System is described in the following quote from a June 1977 article published in Laboratory Medicine entitled "A Positive Blood Recipient Identification System In A General Hospital":
"How The System Works PA0 At the time a transfusion is requested, a transfusion requisition form with an attached sheet of blood tabs and armband containing the key transfusion number is completed. The number of units required plus pertinent clinical information is filled in. For each unit of blood requested, a crossmatch transfusion report is imprinted with the patient's name. PA0 Blood is drawn from the patient after carefully verifying the patient's identification. At this time, the armband, at the bottom of the blood tab sheet, with the key identification number, patient's name, date, and time the blood was drawn is placed on the patient. The tube of blood is labeled with the appropriate specimen tube label also containing the key transfusion number. The blood sample, requisition forms, and crossmatch transfusion forms are then sent to the Blood Bank. PA0 In the blood bank, the technologist completes the typing and crossmatching procedures, labeling the test tube rack with the rack label from the blood tab sheet. At the time the crossmatch is completed, the appropriate information listing the recipient's type and the crossmatch reactions is filled in on the crossmatch transfusion report form. Labels containing the key identification number from the blood tab page are placed on all copies of the crossmatch transfusion reports. The blood unit identification tabs containing the key identification number are then placed on the correct units. PA0 The units available for transfusion are listed on the chart copy of the transfusion requisition form by number and this is then placed on the patient's chart. The identification copy (green) from the crossmatch transfusion form is placed in a "Transfusion Ready" box at the door of the blood bank. PA0 When the ward personnel come to pick up the blood, using appropriate identification, they select the identification forms and present those to the blood bank technologist. The technologist then matches the identification form with the correct unit of blood. The person issuing the blood as well as the person receiving the blood sign the crossmatch transfusion report form, which accompanies each unit. PA0 At the time of starting transfusion, the patient is re-identified, both verbally and visually. The key transfusion numbers are correlated on the patient's armband, on the crossmatch transfusion report forms, and on the units of blood. These key transfusion numbers must agree before the blood transfusion can be started. PA0 Temperature, pulse, and blood pressure are recorded on the crossmatch transfusion form before starting the blood and the patient is carefully observed during the first few minutes of transfusion. Temperature, pulse, and blood pressure are checked again and recorded one hour after starting the blood. The times the transfusion is started and completed are recorded on the transfusion report form. Should any reactions develop, the transfusion is stopped and appropriate procedures for investigating such reactions are instituted, including a recheck of the patient's identification." PA0 "Disadvantages PA0 Several difficulties and problems were pointed out also by the staff and technologists: PA0 Before the Hollister System was begun, errors in patient identification seemed to arise quite commonly, although we could not document the exact frequency. The following brief case reports describe several situations in which identification errors have occurred. PA0 Reports of Errors While Using Hollister System PA0 Case 1: A 41-year-old woman was struck by a car and was brought to the emergency room unconscious. After administration of fluids and blood she became more responsive. She was found to have extensive hip fractures and evidence of bladder rupture. This was repaired surgically. Following surgery, it was thought that she still needed blood replacement. PA0 One unit she was to receive had a donor number 17J61673. Inadvertently, the technologist took 17J61763 which was the same type as the patient (A+). When she noticed the key transfusion number was missing, she thought that this had been omitted by mistake and manually wrote out another tag to place on the unit. This unit was released and administered to the patient without difficulty. When the error was noted, the unit was crossmatched and found to be compatible. PA0 Case 2: A 45-year-old woman had two units of blood crossmatched for routine hysterectomy. When the blood was sent to surgery, the technologist transposed two numbers in an eight-digit donor number, similar to the error made in Case 1. One of the two units released was uncrossmatched, but ABO and Rh compatible. Although this unit lacked the key transfusion number, neither the person issuing nor the person picking up the blood noticed this omission. PA0 The unit soon was missed in the blood bank, the error realized, and the unit recovered from the operating room before being administered to the patient. Had the unit been needed, we would hope that the person administering the blood would have noticed that the key transfusion number was missing from the unit and would not have given it. PA0 Case 3: A 24-year-old man (P. B.) was admitted for extensive second and third degree burns. His early treatment included intravenous fluids and whole blood. An intern drew blood from the patient for crossmatch, put the correct armband on the patient, but handed the blood to the ward secretary to label. She imprinted the label with another patient's name (D. M.), put the label on the tube and sent it to the blood bank. Since P. B. and D. M. previously had been typed and were different ABO types, the discrepancy was detected at the time of crossmatching and a correctly labelled tube was obtained from P. B. Had the patients been the same ABO and Rh type, the error would have been detected at the time of attempted administration to D. M., since P. B. and not D. M. had on the corresponding armband. PA0 Case 4: An elderly man (J. S.) was admitted for TUR. The evening before surgery, the on-call intern who did not know the G.U. patients was called to draw the crossmatch tube. The forms were correctly filled out, but unfortunately he did not verify identification with the patient and drew blood from G. T. instead. T. G. received the armband intended for J. S. Fortunately, both T. G. and J. S. had previously been typed and had different ABO types. A sample was then correctly obtained from J. S. Again, if the error had not been detected in the laboratory, J. S. would not have received the wrong unit of blood in surgery, since he would not have had on the corresponding armband. PA0 . . . PA0 In all four situations where errors in patient identification occurred, the errors never would had arisen if the system had been followed rigidly. We believe that the system is well designed and has the capability of significantly reducing identification errors even in a busy general hospital with a large number of house staff members. PA0 The problem with the system obviously centers around unwillingness or failure of the staff to follow the system completely. It is ineffective and no better than other systems if the entire system is not followed from start to finish. (Emphasis added.)"
While the Ident-A-Blood System described above contains many advantages over no system at all, several disadvantages have been recognized. Some of these disadvantages are described in the following quote from the same article:
1. The extra paper work for the ward personnel, and particularly for the technologists, increased the amount of time involved in crossmatching and transfusing patients. The system initially was thought to be fairly complex when instituted. However, after it had been used for a while, both the extra paper work and the complexity seemed to be only minor problems. PA2 2. The armbands have presented some problems on certain patients. Patients who are receiving large amounts of blood often accumulate several armbands during a short period of time, making it difficult to find room for a new armband and also to find the appropriate armband when a unit of blood is administered. Furthermore, since the armbands are removed after 24 hours, occasionally errors are made and the wrong armband is removed. PA2 3. Probably the most serious problem with the system is that it often is not followed completely, and there is no effective way of insuring that it is followed. The most common error is that a member of the house staff will draw the blood, take the tube to the nurse on the ward, ask her to label the tube, and go back and put the armband on the patient. This obviously defeats the purpose of the system and allows for errors to arise. PA2 4. A minor problem occurs when more than four units are crossmatched on a single tube. Since the forms provide key transfusion numbers for just four units, blank tabs are filled in with the appropriate key transfusion number in the blood bank, if more than four units are to be crossmatched. Having to write in these numbers provides another possible source of error.
Note that the patent and non-patent prior art teachings described above call for identification of the blood type by a sample drawn from the patient and delivered to a laboratory. All subsequent transactions leading ultimately to the transfusion of blood to the patient are dependent upon properly analyzing the blood sample and correlating the results to the individual patient's identity by name or hospital ID number. Also, the prior art, particularly the Ident-A-Blood System, relies upon proper visual verification at several steps in the process. It is an object of the present invention to minimize such opportunities for error. It is also an object of the present invention to provide an improved device and method for prevention of mistranfusion of ABO or Rh incompatible blood.